Metacarpal neck plate

ABSTRACT

A bone plate sized and shaped for fixation to a metacarpal includes a head extending from a first end to a second end and having first and second fixation element holes extending therethrough along first and second fixation element hole axes, wherein the first hole axis diverges from the second hole axis on a bone facing side of the plate, the head having a first notch on the first end centered on the central longitudinal axis, the first notch formed as a indentation on an outer wall of the bone plate sized and shaped to accommodate a collateral ligament when the plate is fixed to a metacarpal in a desired position and a shaft extending from the second end of the head to a third end along the central longitudinal axis, the shaft including an elongated fixation element hole elongated in a direction parallel to the central longitudinal axis.

FIELD OF THE INVENTION

The exemplary embodiments generally relate to plates for the fixation offractures of bones in the hand and methods of implanting these plates onbone.

BACKGROUND

Current systems and methods for the fixation of certain fractures arelimited in the placement and orientation of bone fixation plates overthe bone. For example, plates for the fixation of fractures of the fifthmetacarpal are confined to a limited placement of the plate dictatedheavily by the construction of the plate and not by the location/type ofthe fracture or an optimized position that might be selected by asurgeon absent these limitations imposed by the plate construction. Morespecifically, plates for fixation of fractures of the fifth metacarpal,also known as boxer's fractures, are generally limited to a placementover only predetermined portion of a lateral surface of the bone with afirst portion of the plate being dorsal and a second portion of theplate being lateral. Depending on the type of fracture, this placementmay not be optimal and limiting placement to this arrangement does notprovide the surgeon with the freedom to select an optimal placement formany fracture types.

SUMMARY

The exemplary embodiments are directed to a bone plate sized and shapedfor fixation to a metacarpal comprising a head extending from a firstend to a second end and having first and second fixation element holesextending therethrough along first and second fixation element holeaxes, wherein the first hole axis diverges from the second hole axis ona bone facing side of the plate, the head having a first notch on thefirst end centered on the central longitudinal axis, the first notchformed as a indentation on an outer wall of the bone plate sized andshaped to accommodate a collateral ligament when the plate is fixed to ametacarpal in a desired position and a shaft extending from the secondend of the head to a third end along the central longitudinal axis, theshaft including an elongated fixation element hole elongated in adirection parallel to the central longitudinal axis.

BRIEF DESCRIPTION OF THE DRAWINGS

Several embodiments will be described in the following by way of exampleand with reference to the accompanying drawings in which:

FIG. 1 shows a first perspective view of a bone plate according to anexemplary embodiment;

FIG. 2 shows a first lateral view of the bone plate of FIG. 1;

FIG. 3 shows a second lateral view of the bone plate of FIG. 1; and

FIG. 4 shows a second perspective view of the bone plate of FIG. 1.

DETAILED DESCRIPTION

The exemplary embodiments may be further understood with reference tothe following description and the appended drawings, wherein likeelements are referred to with the same reference numerals. The exemplaryembodiments relate to apparatus and methods for the treatment offractures and, in particular, to devices for fixing fracture of thefifth metacarpal. More specifically, the exemplary bone fixation platesmay be used for the fixation of unstable subcapital comminuted head andneck fractures of the metacarpals. Exemplary embodiments describe a bonefixation plate having a head and an elongated shaft, which plate ispositionable against an outer surface of a fractured or otherwisedamaged bone. The exemplary head of the bone plate is formed in a “y”shape having first and second sides separated by a substantially roundednotch aligned with a central longitudinal axis of the plate. The notchis sized and shaped so that when the plate is positioned over a targetportion of the fifth metacarpal, a collateral ligament is received innotch, limiting interference from the plate with surrounding ligamentsand tissues. The head includes five variable angle fixation elementholes in a grid formation and having hole axes diverging away from oneanother, as will be described in greater detail later on. A bonecontacting surface of the head is formed with a curvature selected toconform to a curvature of the metacarpal to ensure flush seating of theplate thereover. The head further includes a guide wire hole sized andshaped to receive a guide wire such as a Kirschner wire. The shaft isformed with a webbed shape and has a plurality of variable anglefixation element holes and an elongated compression hole. As will bedescribed in greater detail later on, the exemplary shape, size andcontour of the exemplary bone plate permits the bone plate to bepositioned further dorsally on the fifth metacarpal than plates incurrently available systems. It is noted that although the exemplarysystem and method are directed to fixation of fractures of a fifthmetacarpal, the exemplary bone fixation system may be used in any othermetacarpal without deviating from the scope of the invention. It shouldbe noted that the terms “proximal” and “distal” as used herein, refer toa direction toward (proximal) and away from (distal) a core of the body.For example, a direction from the hand to the elbow is proximal while adirection from the elbow to the hand is distal. Furthermore, when usingthese terms in reference to a plate to be attached to a bone, proximalwill refer to a direction along the plate when it is attached to atarget bone in a desired orientation.

As shown in FIGS. 1-3, an exemplary bone plate 100 extends from a firstend 102 including a head 104 to a second end 106 including a shaft 108along a central longitudinal axis 110. The head 104 has a substantiallytriangular shape with a first width at the first end 102 and a second,smaller width at a junction portion 112. A notch 114 at the first end102 has a substantially rounded shape and is substantially aligned withthe longitudinal axis 110. In an exemplary embodiment, a shape of thenotch 114 corresponds to an arc of a circle. In one embodiment, thenotch 114 has a radius of curvature of 1.5 mm. However, alternativeembodiments may be formed with a radius of curvature of up to 3 mmwithout deviating from the scope of the invention. As would beunderstood by those skilled in the art, a radius of curvature of thenotch 114 may be selected to correspond to dimensions of a ligament tobe received in the notch when the plate 100 is implanted. For example,the notch 114 may be sized such that, when implanted on a fifthmetacarpal, a collateral ligament attaches to the bone at a point withinthe notch 114, so that the ligament passes over the plate 100 minimizingthe discomfort associated with interference from the bone plate withligaments post-implantation while permitting placement of the bone plate100 further dorsally on the bone. In another embodiment, the notch 114may have a non-circular shape (e.g., oblong, etc.) without deviatingfrom the scope of the invention.

The head 104 also includes a K-wire hole 116 extending therethrough toguide placement of the bone plate 100 over a target portion of the bone.As those skilled in the art will understand, K-wires are notconventionally passed through bone plates for the fixation of metacarpalfractures. In contrast, conventional bone plates for the fixation ofmetacarpal fractures are typically manually positioned over the bone andheld in place by hand or with forceps. In an exemplary embodiment, theK-wire hole 116 is aligned with the central longitudinal axis 110 andextends from the top surface 118 to a bone contacting surface 120 at anangle that is not orthogonal to the top surface 118. In a preferredembodiment, the K-wire hole 116 is angled so that an end of a wire whichhas passed through the hole 116 toward the bone will extend toward theend of the plate 100 including the notch 114. The K-wire hole 116according to this embodiment has a diameter of, for example, 1.0 mm toaccommodate K-wires having a diameter of 1.0 mm or smaller.

The bone contacting surface 120 of the head 104 is formed with acurvature selected to conform to the curvature of the metacarpal toensure flush seating of the bone plate thereover. In one embodiment, thebone contacting surface 120 of the head 104 has a radius of curvature of5 mm. In another embodiment, the bone-contacting surface 120 includes aplurality of curvatures corresponding to the surface of the bone.

The head 104 also comprises a plurality of fixation element holes 122,124, 126, 128, 130. The fixation element holes 122, 124, 126, 128 extendthrough the plate 100 along hole axes angled to diverge from one anotheron a bone facing side of the plate 100. The holes 122, 124 aresymmetrically positioned with respect to the longitudinal axis 110 andextend through the bone plate 100 at opposing angles. For example, inone embodiment, the hole axes 123, 125 of the fixation element holes122, 124, respectively, enclose an angle α of 31 degrees. It is noted,however, that this value is exemplary only and a plurality of othervalues for α may be employed without deviating from the scope of theinvention. For example, the angle α may be 0-45 degrees. The fixationelement holes 126, 128 are also symmetrical with respect to thelongitudinal axis 110 and extend through the bone plate 100 at opposingangles. For example, in one embodiment the hole axes 127, 129 of thefixation element holes 126, 128, respectively, enclose an angle β of 4degrees. It is noted, however, that this value is exemplary only and aplurality of other values for β may be employed without deviating fromthe scope of the invention. For example, the angle β may be 0-10degrees. The four diverging screw trajectories defined by bone platehole axes 123, 125, 127, 129 are designed to capture common fracturepatterns of the metacarpals while avoiding the articular surface of thebone. The fixation element holes 122, 124, 126, 128 are formed asvariable angle holes to permit the bone screws to be locked at anyangulation within a predefined range of angulation (e.g., ±15°) relativeto their hole axes 123, 125, 127, 129 as would be understood by thoseskilled in the art. This configuration permits the surgeon to alter theangle of insertion as needed to capture hard to reach fracturefragments. The fixation element hole 130 is centered about thelongitudinal axis 110 and is also formed as a variable angle hole withsubstantially the same structure and operation as the fixation elementholes 122, 124, 126, 128 described above. A bone plate hole axis 131 ofthe bone plate hole 130 extends orthogonally to the top surface 118. Inthis embodiment, the fixation element holes 122, 124, 126, 128, 130 aresized to lockingly receive the heads of 1.5 mm variable angle lockingscrews, although other dimensions are envisioned within the scope of theinvention.

The shaft 106 includes an elongated compression hole 132 centered on theshaft 106 and elongated in a direction parallel to the longitudinal axis110. The compression hole 132 allows for plate adjustment after a bonescrew (not shown) has been provisionally inserted therethrough into thebone (i.e., prior to tightening of the bone screw within the compressionhole 132). The compression hole 132 includes an increased diameter lip134 formed to seat an enlarged diameter head of a bone screw (not shown)therein. The shaft 106 also includes variable angle fixation elementholes 136, 138 having bone plate hole axes extending orthogonal to thetop surface 118, wherein bone screws inserted through the fixationelement holes 136, 138 may be angled within a predetermined rangerelative to the bone plate hole axes, as described in greater detailabove. The fixation element holes 136, 138 are also centered about thelongitudinal axis 110. The fixation element holes 136, 138 in thisembodiment are also sized to lockingly receive the heads of 1.5 mmvariable angle locking screws, although other dimensions are envisionedwithin the scope of the invention.

The shaft 106 also includes a plurality of first webbed portions 140extending along a first side wall 141 between each of the holes 130,132, 136, 138 and a plurality of second webbed portions 142 extendingalong a second side wall 143 between each of the holes 130, 132, 136,138. The first and second webbed portions 140, 142 are formed as notchesextending into the bone plate 100 to reduce a profile thereof whilemaintaining the structural integrity of the bone plate 100. The firstand second webbed portions 140, 142 are sized such that a minimumclearance remains at the boundary of each of the plate holes 130, 132,136, 138. As shown in FIG. 4, the outer periphery 144 of the bone plate100 may include a rounded taper to further reduce the profile.

In accordance with an exemplary method, a K-wire (not shown) is insertedinto a target portion of the bone. The free end of the K-wire isslidably received in the K-wire hole 116 to guide provisionalpositioning of the bone plate 100 over the bone. In an exemplaryembodiment, the bone plate 100 is positioned over a lateral surface ofthe fifth metacarpal or on a dorsolateral surface of the second, thirdor fourth metacarpal. The head 104 is positioned over the neck of themetacarpal while the shaft extends distally therefrom (i.e., in adirection extending toward a distal end of the finger). A bone fixationelement such as a bone screw (not shown) is then inserted into thecompression hole 132. The bone plate 100 may then be repositioned ifneeded by sliding the bone plate 100 over the bone within a range ofmotion defined by the length of the compression hole 132. Once the boneplate 100 has been moved to a desired final position over the bone, bonescrews (not shown) are inserted into one or both of the fixation elementholes 122, 124, followed by insertion of bone screw (not shown) into anyof the fixation element holes 126, 128, 130, 136, 138 in accordance withthe requirements of the procedure (e.g., according to the fracturepattern).

It will be appreciated by those skilled in the art that variousmodifications and alterations of the disclosed embodiments may be madewithout departing from the broad scope of the invention. Some of thesehave been discussed above and others will be apparent to those skilledin the art.

What is claimed is:
 1. A bone plate sized and shaped for fixation to ametacarpal, comprising: a head extending from a first end to a secondend and having first and second fixation element holes extendingtherethrough along first and second fixation element hole axes, whereinthe first hole axis diverges from the second hole axis on a bone facingside of the plate, the head having a first notch on the first endcentered on the central longitudinal axis, the first notch formed as aindentation on an outer wall of the bone plate sized and shaped toaccommodate a collateral ligament when the plate is fixed to ametacarpal in a desired position; and a shaft extending from the secondend of the head to a third end along the central longitudinal axis, theshaft including an elongated fixation element hole elongated in adirection parallel to the central longitudinal axis.
 2. The bonefixation plate of claim 1, wherein a shape of the bone facing surface ofthe head conforms to a contour of a metacarpal to which it is to befixed.
 3. The bone fixation plate of claim 1, wherein the head and shaftare sized and shaped for fixation laterally over a fifth metacarpal. 4.The bone fixation plate of claim 1, wherein the head further comprisesthird and fourth fixation element holes extending therethrough alongthird and fourth hole axes, respectively, wherein the first, second,third and fourth hole axes diverge from one another on the bone facingside of the head.
 5. The bone fixation plate of claim 4, wherein thethird and fourth fixation element holes are symmetric with respect tothe central longitudinal axis, the third hole axis being complementaryto the fourth hole axis.
 6. The bone fixation plate of claim 5, whereinthe head further comprises a fifth fixation element hole having defininga fifth hole axis orthogonal to a plane in which the shaft is located.7. The bone fixation plate of claim 6, wherein the shaft includes sixthand seventh fixation element holes extending therethrough along sixthand seventh hole axes, respectively.
 8. The bone fixation plate of claim7, wherein the shaft includes plurality of second notches formed infirst and second lateral walls thereof, the second notches definingreduced width regions of the shaft.
 9. The bone fixation plate of claim8, wherein the second notches are located along the length of the shaftbetween adjacent ones of the fourth fixation element hole, the elongatedhole, the sixth fixation element hole and the seventh fixation elementhole.
 10. The bone fixation plate of claim 1, wherein the head is angledaway from a plane of the shaft.
 11. The bone fixation plate of claim 1,further comprising a tapered region extending around a periphery of thebone plate to reduce a profile thereof.
 12. The bone fixation plate ofclaim 1, wherein the first and second hole axes are symmetric withrespect to the central longitudinal axis, the first hole axis beingcomplementary to the second hole axis.
 13. The bone fixation plate ofclaim 1, further comprising a guide-wire hole extending through thehead.